Charmed ${\Lambda }_c^{+}$ baryon decays into light scalar mesons in the topological $SU(3{)}_f$ framework

Abstract

Using the topological-diagram approach based on $SU(3)$ flavor symmetry, we investigate two-body ${\Lambda }_c^{+}\to \mathbf{B}S$ decays, where $\mathbf{B}$ denotes the final-state baryon and $S$ refers to a light scalar meson, such as $f_0/f_0(980)$, $a_0/a_0(980)$, ${\sigma }_0/f_0(500)$, or $\kappa /K_0^{\ast }(700)$. Our analysis indicates that interpreting the light scalar mesons as tetraquark states provides a more consistent description of the currently available experimental data. In particular, this framework naturally accommodates the experimentally observed branching fraction $\mathcal{B}({\Lambda }_c^{+}\to \Lambda a_0^{+})$, which exceeds predictions based solely on long-distance effects by an order of magnitude. Within the tetraquark scenario, we predict $\mathcal{B}({\Lambda }_c^{+}\to {\Sigma }^{+}{f}_0)=(4.9\pm 1.9)\times 10^{-2}$ and $\mathcal{B}({\Lambda }_c^{+}\to p{f}_0)=(3.6\pm 1.4)\times 10^{-3}$. Owing to $f_0-{\sigma }_0$ mixing, $\mathcal{B}({\Lambda }_c^{+}\to {\Sigma }^{+}{\sigma }_0)$ and $\mathcal{B}({\Lambda }_c^{+}\to p{\sigma }_0)$ are suppressed to the levels of $1\times 10^{-3}$ and $5\times 10^{-5}$, respectively. These modes therefore provide sensitive probes of the internal structure of the light scalar mesons. More generally, the remaining branching ratios of ${\Lambda }_c^{+}\to \mathbf{B}S$ are found to be comparable to those of ${\Lambda }_c^{+}\to \mathbf{B}M$, where $M$ denotes a pseudoscalar meson. Their predicted sizes suggest that these decay modes should be accessible to ongoing and near-future experimental studies at BESIII, Belle II, and LHCb.

Comments: 21 pages, 1 figure, 3 tables; to appear in JHEP